Radial flow impelllers for centrifugal pumps or fans



May 21, 1963 J. c. BUSQUET RADIAL FLOW IMPELLERS FOR CENTRIFUGAL PUMPS OR FANS Filed Dec. 8, 1960 FIG.2

FIG.1

P164 in FI INVENTOR (1M CBz/sa UET ORNEY 3,090,543 RADIAL FLOW ELLERS FOR CENTRIFUGAL PUMPS R FANS Jan C. Busquet, Hengeio, Netherlands, assignor to Koninklijke Machinefabriek Gebr. Stork & Co. N .V., Hengelo, Netherlands Filed Dec. 8, 1960, Ser. No. 74,717 Claims priority, application Netherlands Dec. 24, 1959 4 Claims. (Cl. 230-114) This invention relates to a radial flow impeller for a centrifugal pump or fan, having at least one supporting plate for the blades, which each consist of two mutually adjustable parts, one of said parts of each blade being rigidly connected to the supporting plate or plates and the other part being pivotal with respect to said first part. By adjusting said pivotal blade parts of such an impeller the capacity of the fan or pump may be varied.

The impellers of this kind known up to now suffer the drawback that in consequence of the very heavy centrifugal forces acting on the blades the adjustable blade parts are blocked up, so that during operation adjustment of said blade parts will not be possible.

The invention has for its object to provide a radial impeller having adjustable blades which can not be blocked up, so that the blades may be adjusted during operation. To this end according to the invention only contact along a line occurs in the pivot of the adjustable blade part in such a manner that there is no sliding friction in said pivot and the adjusting means of the pivotal blade part are provided with at least one inflatable bellows placed between the pivotal blade part and an element rigidly secured to the impeller. It appeared namely that blocking up of the pivotal blade parts is caused by friction resistance due to the very high specific pressure occurring in the pivot, said friction resistance being attended with sliding friction.

If sliding friction is avoided in the pivot of the adjustable blade parts there will not occur large counteracting forces notwithstanding the heavy specific pressure in the pivot provided that the pivotal blade parts are correctly balanced. Sliding friction in the adjusting means will also be prevented, so that indirect blocking up of the pivotal blade parts under the influence of the centrifugal forces acting on said adjusting means cannot occur. The pivotal part of the blade is so designed that the centrifugal forces acting on said blade part are only partly balancing each other so that the resulting force tends to rotate the pivotal blade part in a direction opposite to the direction of the rotation caused by the bellows.

The invention will further be described with reference to the accompanying drawing illustrating two embodiments of the impeller according to the invention.

FIG. 1 is a cross-sectional view of the impeller according to a first embodiment.

FIG. 2 shows a section taken on line 11-11 of FIG. 1.

FIG. 3 is a cross section of part of a blade on enlarged scale.

FIG. 4 shows a similar cross section of part of a blade according to the second embodiment.

FIG. 5 is a section taken on line VV of FIG. 3 and FIG. 6 is a section taken on line VI-VI of FIG. 4

In the drawing 1 denotes one of the supporting plates which is provided with a circular inlet opening for the fluid to be propelled. A second supporting plate for the impeller blades is denoted by 3 and said plate being secured to the shaft 4 of the pump or fan. The blades are placed between the plates 1 and 3 and consist each of a part 5 rigidly connected to the supporting plates and of a pivotal part 6. The blade parts 5 and 6 together constitute an aerofoil section.

As shown in FIGS. 3 and 5 the pivotal blade part 6 on both sides is provided with a projection 7 forming a journal resting in a cup-shaped element 8 secured to each of the supporting plates 1 and 3. Secured to the supporting plates 1 and 3 are abutrnents 9 and 10 between which the blade part 6 can pivot. The radius of curvature in a cross section of the journal 7 in the point of contact with the cup 8 is smaller than the radius of the cup is said point, in such a manner that upon rotation of the blade part the journal rolls in the cup. With said arrangement only rolling friction occurs in the pivot. The Wall portion of the blade part 6 at the front of the blade is provided with an extension 11. The rigid blade part 5 has an extension 12 at the rear and the extensions 11 and 12 consistitute parts of the active surfaces of the blade between the rigid blade part 5 and the pivotal part 6. A tube-shaped bellows 13 is placed between said extensions 11 and 12. Said bellows 13 extends on the whole width of the blade 5, 6 and projects through the supporting plate 3 to the outside of the impeller in order to be connected to an air conduit 14 which itself is connected to a supply channel provided in the shaft 4 of the impeller. In this way through said channel in the shaft 4 air may be introduced into the elastic tube 13.

The pivotal blade part 6 is designed so as to enable said blade part to tend to move against the abutment 10 under the influence of the centrifugal forces during operation of the impeller, so that the tube 13 is compressed. If new compressed air through conduit 14 is introduced into tube 13 the blade part 6 will be rotated against the action of the centrifugal force and in proportion to the quantity of compressed air supplied will assume a position intermediate the abutments 9 and 10 or against the abutment 9.

When the pivotal blade part 6 is correctly designed it will be possible that the resulting centrifugal forces exerts a small moment only on said blade part, so that the tube 13 has only to generate a small adjusting force. As the journal 7 performs a rolling, rather than sliding, movement in the cup 8 the adjusting force will only depend on the moment exerted on the blade part 6 notwithstanding the large resulting centrifugal force pressing the journal 7 on the wall of the cup.

FIGS. 4 and 6 shows a modified construction of the pivot according to which the cylindrical journal 7 and the cup 8 of the pivot are replaced by a knife edge 15 and a pan 16. With this arrangement also, there will be no sliding friction in the pivot.

The extension 11 of the adjustable blade part 6 is bent inwards, whereby in all positions of said blade part a favourable aerodynamical section of the active blade surface is obtained. The flow of fluid along the rigid blade part 5 is then guided by the curved extension 11 without occurring sudden changes of the direction of flow.

What I claim is:

1. A radial flow impeller for a centrifugal pump or the like comprising at least one rotatable supporting plate, blades secured to said plate, each blade including a fixed leading part rigidly secured to the rotatable supporting plate and an adjustable trailing part angularly movable relative to a radius of the impeller, pivot means support ing said adjustable blade part on said plate, said pivot means including a first element fixed to said supporting plate and an opposed second element fixed to the leading portion of said trailing part radially inwardly of said first element, said first element having a substantially larger radius of curvature than said second element and engaging the second element on a single line contact only for reduction of friction during relative rotation of the elements, and an inflatable bellows bearing against the leading portion of said adjustable blade part to move the part in a direction opposite motion caused by centrifugal action.

2. A radial flow impeller for a centrifugal pump according to claim 1 wherein the said first element of the pivot means comprises a pan-shaped surface and said second element comprises a knife edge.

3. A radial flow impeller for a centrifugal pump according .to claim 'lwherein a part of the Wall (if the adjustable blade part forming the active surface of the blade is extended towards the fixed blade part and a part of the opposite Wall of said fixed blade part is extended towards the adjustable blade part so that said extended wall parts overlap, and said inflatable bellows being located between said extended wall parts of the blade.

4. A radial flow impeller for a centrifugal pump according to claim 3 wherein said bellows is constituted 4, by a tube of elastic material placed between said extended wall part of the blade parts and extending the entire Width of the blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,351,516 Jandasek June 13, 1944 2,753,835 Gehrig July 10, 1956 2,935,245 McDonald May3, 1960 3,006,534 McDonald Oct. 31, 1961 v FOREIGN PATENTS 214,419 Australia April 8, 1958 457,243 Germany March 10, 1928 1,148,127 France June 17, 1957 

1. A RADIAL FLOW IMPELLER FOR A CENTRIFUGAL PUMP OR THE LIKE COMPRISING AT LEAST ONE ROTATABLE SUPPORTING PLATE, BLADES SECURED TO SAID PLATE, EACH BLADE INCLUDING A FIXED LEADING PART RIGIDLY SECURED TO THE ROTATABLE SUPPORTING PLATE AND AN ADJUSTABLE TRAILING PART ANGULARLY MOVABLE RELATIVE TO A RADIUS OF THE IMPELLER, PIVOT MEANS SUPPORTING SAID ADJUSTABLE BLADE PART ON SAID PLATE, SAID PIVOT MEANS INCLUDING A FIRST ELEMENT FIXED TO SAID SUPPORTING PLATE AND AN OPPOSED SECOND ELEMENT FIXED TO THE LEADING PORTION OF SAID TRAILING PART RADIALLY INWARDLY OF SAID 